In general, a diesel engine is operated using fuel such as heavy oil, light oil, etc., which are cheaper than fuel used in a gasoline engine, and reduces fuel consumption, so that the diesel engine has an advantage of low operational cost. In addition, the diesel engine can be easily operated, so the diesel engine is widely used as an internal combustion engine.
A large-sized diesel engine is used as a main engine of a large-sized ship, a middle-sized diesel engine is used for a power generator and a ship, and a small-sized diesel engine is used for a vehicle, a rail road car, a small-sized ship, a construction equipment, etc. That is, the diesel engine is extensively used in various fields. In addition, the diesel engine is used for a cultivator, a pump spray for irrigation work in agriculture, a compressor, a power water pump, and emergency communication power.
As widely known to the public, the diesel engine using light oil as fuel produces sooty smoke upon incomplete combustion. Especially, in the case of the vehicle, when the vehicle runs along a hill or a driver strongly steps on an accelerating pedal, the sooty smoke is excessively produced. In addition, as described above, if the sooty smoke is excessively produced, the output of the vehicle is remarkably lowered and the emitted sooty smoke causes serious environmental pollution.
In order to overcome the above problems, various methods for heating and preheating fuel have been developed. For instance, in the case of a small-sized vehicle, a heating member or a typical burner is mounted on an outer part of the a fuel supply pipe, which is used to supply fuel contained in a fuel tank to the engine, thereby heating and preheating fuel to supply the fuel to the engine. In the case of a large-sized vehicle, the fuel supply is electronically controlled to prevent sooty smoke.